(a) Field of the Invention
The present inventions relates to an over-current damage prevention method and apparatus for a subsidiary inverter of an electric bus, which may prevent generation of over-current in the subsidiary inverter of the electric bus when a clutch of an air compressor is connected thereon.
(b) Description of the Related Art
The importance of maintaining a green environment has recently been increasing and as such, low-floor buses using natural gas (e.g., other than petroleum-based fuel) are operating in cities. Many car manufacturers have developed electric buses as a next-generation transportation means.
A series of battery packs may be mounted in the body of an electric bus to drive the driving wheels through a motor receiving electric power supplied from the battery packs and to drive various types of auxiliary machinery apparatuses, such as a steering apparatus and a cooling apparatus.
FIG. 1 is an exemplary schematic view illustrating a power network configuration of an electric bus, according to the related art. FIG. 2 is an exemplary configuration illustrating a configuration of an auxiliary inverter of the electric bus, according to the related art.
The voltage of a high-voltage battery 1 of the electric bus may be applied to a 230V DC/AC auxiliary machinery inverter 3 through a high-voltage junction box 2, and the auxiliary machinery inverter 3 may convert a DC voltage of 380V, applied from the battery 1, into an AC voltage of 230V. Auxiliary machinery, such as an air compressor and power steering pump 4 and a water pump, 5 may be driven by receiving the converted AC voltage from the auxiliary machinery inverter 3.
In this case, after the electric bus starts moving, a power steering motor 6 may be rotated at a high speed, an air compressor 8 may be connected to the power steering motor 6 by a belt, and a clutch 7 may be mounted to the air compressor 8. When the clutch 7 is engaged, the air compressor may be operated by receiving power from the belt.
The operating condition of the air compressor 8 will now be described. When the pressure of an air tank is lower than a setup value (e.g., 8 Bar), gas stored in the air tank may be compressed under the operation of the air compressor 8. Moreover, when the pressure of the air tank is higher than the setup value, the operation of the air compressor 8 may be stopped.
However, when the power steering motor 6 is rotated at the high speed, the air compressor 8 may operate while the clutch 7 is engaged. In this case, surge current may be generated due to the abrupt occurrence of a load, thus, the inverter 3 that applies electric power to the auxiliary machinery may be damaged.
The above information is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art.